Reciprocating saws are provided with a shoe which permits the operator to position the saw relative to the work being cut. As is known to those who are experienced in using such tools, for a particular application there is an optimum position for the shoe. Adjustment of the shoe makes plunge and pocket cuts easier and extends the blade life by cutting with different areas of the blade.
A typical shoe support is secured into position with adjusting screws. These screws pass through slots in the shoe support and thread into the front end of the gear housing clamping the support and shoe in the desired position. Adjustment of the shoe position requires the use of a separate tool, such as a screwdriver. This adjustment procedure is often not performed by the operator because the procedure consumes appreciable time and is cumbersome. Moreover, the separate tool necessary to loosen or tighten the screws is, more often than not, lost or misplaced. Consequently, optimum positioning of the shoe for a given application may often not be achieved.
Another form of guide shoe adjustment mechanism is shown in U.S. Pat. No. 5,007,172, which issued on Apr. 16, 1991 to Bernard Palm. According to the disclosure in that patent, adjustment is accomplished by rotating a lever. Attached to this lever is a lock pin which is pivotally mounted in the front end of the gear housing transverse to the shoe support. The pin's geometry comprises a "D" shaped formation having the rounded portion thereof adapted for engagement in a selected one of three arcuate grooves formed in the support to secure the support, and hence the shoe, into the desired position. To release and reposition the shoe, the lever is rotated allowing the flat portion of the pin to be parallel with the flat portion of the support thereby providing clearance which permits the support and shoe to move freely. When the shoe has been moved to its desired position, the lever is rotated back enabling the rounded portion of the pin to engage and be received in the selected arcuate groove in the support thereby to establish the new position for the shoe.
There are several disadvantages with the mechanism disclosed in U.S. Pat. No. 5,007,172. First, when the actuating lever is in the "lock" position, friction must be relied upon to hold the lever in place. The amount of friction available diminishes with usage over time because of wear. When the friction diminishes the support gains freedom of movement, appearing loose or insecure, thereby increasing the chances of having a locking pin becoming mistakenly disengaged due to looseness. Secondly, the particular design under discussion does not incorporate a self-locating action for the locking pin to align itself with the arcuate grooves in the support. The operator must jiggle the support to "feel" the position wherein the rounded portion of the pin will be received in one of the arcuate recesses in the support. Third, the shoe support according to this prior art design is in the form of a post with flats and grooves and is thus expensive to manufacture.